Foo was a nonsense word used by cartoonist Bill Holman in the comic strip "Smokey Stover" from the 30's into the 50's. He was reported to have discovered the word in a Chinese fortune cookie and the word appeared in almost every panel in the strip. It predates most of definitions that I have seen so far. The strip appeared in the SF Chronicle or the SF Examiner.

Foo was on signs along the road, on license plates or anywhere else one could imagine

Abreviated version of american rock band Foo Fighters should only be used by real fans. and not wannabe fans that think they do. The foos along with frontman Dave Grohl are an extremely origional and amazing american rock band. The b est American rock band of this age

The Foos are over-rated
theyre not over rated you emo b*stard! you probably think fall out boy and My chemical romance are good, well F*CK YOU! Dave Grohl is a true guitar hero. FOO FIGHTERS SAVING ROCK FROM THE EMO F*UCKHEADS